So far I had no new levels sales, only subscriptions and old 2010 credit sales.New buyers haven't found me yet.

I don't think there are new credit prices, so they still appear as 2010 Credits (as proof I have a level 0 sale with 2010 credits). Same for subs. So no level 0 sales only proves that new buyers haven't found your unsold images. You could have a bunch of subs and level 1-5 sales from new buyers and never know it.

I've had 2 level 0 credit sales so far. Being exclusive, it doesn't make any difference in my royalties...